QTLs for Rice Leaf Chlorophyll Content Under Low N Stress

Quantitative trait loci (QTLs) for chlorophyll content of a rice leaf were mapped on to the molecular marker linkagemap of a double-haploid (DH) population derived from a cross between two rice varieties ‘IR64' and‘Azucena' in bothnutrient solution and soil culture experiments to detect rice nitrogen nutrition status under low N stress. A chlorophyllmeter was used to measure the soil plant analysis development (SPAD) value of the topmost fully expanded leaf as theindex of chlorophyll content that expressed nitrogen status in rice plants. Totally 3 QTLs for SPAD values, two onchromosome 3 located at interval RG179-CDO337 and RG348-RZ329, respectively, and one on chromosome 10 at intervalRZ500-RG134, were detected under stressed conditions of low N in the soil and/or nutrient solution culture experiments.One QTL located at interval RG179-CDO337 on chromosome 3 associated with a relative change in SPAD value from ahigh N level to a low N level in the soil culture experiment was also detected. Based on the different responses to low Nstress between the two parents, it was supposed that the QTLs identified in this study associated with nitrogen efficiencyin rice at low N levels might be useful in applying marker technology to rice breeding programs.